Effects due to Magnetization. 447 



liquid, and the magnet excited, a momentary "throw" of the 

 galvanometer was observed in the direction indicating the 

 point as being protected or acting as the copper of the cell. 



When the pointed pole was slightly flattened at the end, 

 and the insulation so cut away that the surfaces of exposure 

 on the two electrodes were exactly the same, the throw of the 

 galvanometer on making the Held was very much diminished, 

 although still perceptible, since the disposition of lines of force 

 would still be very different over the two plane surfaces of 

 exposure. 



With ball and point electrodes precisely similar phenomena 

 were observed as witli a disc and point, except to a less degree. 



The gradual reversal of the current shortly after exciting 

 the field ; the independence of the throw of the direction of 

 the current through the magnet ; the disappearance of the 

 throw when the nature of the magnetic field at the exposed 

 parts became the same ; and the effects of artificially stirring 

 the liquid were observed exactly as described by Messrs. 

 Rowland and Bell. 



In the course of a large number of preliminary experiments 

 with nitric acid, it was soon observed that under certain condi- 

 tions the effect of suddenly putting on the magnetic field, was 

 to produce a less rapid deflection of the galvanometer in the 

 opposite direction, or indicating the point as acting as a zinc. 

 Plainly this irregular behavior, due to the magnet, required a 

 more systematic study than it had yet received. It had been 

 found that the reversal of the current which regularly fol- 

 lowed the " protective throw " was decreased or destroyed by 

 anything which prevented free circulation in the liquid, and 

 that an acidulated gelatine, which was allowed to harden 

 around the poles, was best suited for this purpose. The great 

 irregularity observed in any one experiment made it necessary 

 to eliminate everything possible which might mask the true 

 phenomenon, if any accurate comparisons were to be drawn 

 between the effects observed in the different cases, accordingly 

 a standard form of experiment was adopted which was care- 

 fully repeated many times. The cell found best suited for 

 this purpose was composed as follows : 



Disc electrode, diameter 14-4.mm 



thickness _. 2 -6 mm 



Point electrode, total length. l.V2 mm 



diameter 4-4™™ 



length of point 5'2 mm 



Distance of point from center of dise 10" mm 



The same electrodes were used throughout any set of experi- 

 ments, being carefully cleaned and polished each time. 



